The present invention relates to a shield assembly for a built-in lens set, and more particularly to a shield assembly that has a shield ring and elastic elements to couple the lens set with a housing for preventing light interference, reducing dust contamination, and enhancing positioning and supporting of the lens set.
Nowadays, a wide variety of image projecting or capturing devices are available on the market. Among them, there is one type that has a built-in lens set. The image projecting or capturing device that has a built-in lens set generally includes a housing to form the device body. Then, various elements can be built in the housing; including a lens set, an image unit, a power supply unit, a control unit and so on. Typically, the housing has an aperture corresponding to the inside lens set for optical images to be input or output.
Refer to FIGS. 1 and 2 for the relationship of the housing and the lens set of a conventional image projecting or capturing device. The lens set 2 as shown includes an optical head 21 that has an outer rim 210. The housing 1 has an aperture 11 corresponding to the optical head 21 for inputting or outputting of optical images. The aperture 11 is formed on an inner rim 10 of the housing 1 and can have a protrusive enclosure 110 extending towards the optical head 21 of the lens set 2 for a preset distance.
As shown in FIGS. 1 and 2, the protrusive enclosure 110 can shorten the spacing between the optical head 21 of the lens set 2 and the aperture 11, and thus can reduce possible light interference upon the lens set or dusts contamination inside the device body. However, to meet the requirements of assembly allowance and focusing adjustment of the lens set 2 (through a focusing ring 22 or other control elements), there is always a gap xcex4 between the optical head 21 of the lens set 2 and a front edge 111 of the protrusive enclosure 110. The gap xcex4 is variable for the focus of the lens set 2 can be arbitrarily adjusted.
In the conventional techniques set forth above, the lens set 2 is constructed like a short suspending cantilever beam with its free end close to the housing 1, and with the gap xcex4 located between the optical head 21 and the front edge 111 of the protrusive enclosure 110. As a result, a number of problems as follows may incur.
1. The gap xcex4 between the optical head 21 of the lens set 2 and the protrusive enclosure 110 of the housing 1 becomes a pathway for dusts contamination. External dusts can drift into the housing 1 through the gap xcex4. When dusts accumulate on the device body for a substantial term, elements inside the device will tend to be contaminated. It could even result in wear-off of elements and malfunction of electric systems.
2. The gap xcex4 between the optical head 21 of the lens set 2 and the enclosure 110 of the housing 1 can be enlarged or shrunk upon adjusting of the focus. When the gap xcex4 is enlarged, extra light interference will incur and optical signals of image input or output between the lens set 2 and the protrusive enclosure 110 of the housing 1 will be affected to some extent.
3. For a zoom lens set 2, the optical head 21 of the lens set 2 is suspended freely. It is not a secured engaging condition relative to the focus adjustment mechanism of the device body. When utilizing for a long period of time, the backlash between driving gears will tend to increase. As a result, controllability of focus adjustment will suffer.
4. There is no common support or linkage between the housing 1 and the lens set 2. The relative position between the optical head 21 of the lens set 2 and the protrusive enclosure 110 of the housing 1 is prone to be offset under various changing factors such as service time, offsetting of the lens set 2 mounting dock, or deformation of the housing 1, and so on. As a result, optical signals of image input or output between the lens set 2 and the aperture 11 of the housing 1 will incur deviations.
While some of aforesaid problems might be assumed by users as natural consequences resulting from aging of the device, yet, from manufacturers"" point of view, there is still a room for improvement.
Accordingly, the primary object of the present invention is to provide a shield assembly for a built-in lens set that has an elastic connecting unit located between the lens set and the housing to restrain light interference, to prevent dust contamination, and to maintain proper alignment between the lens set and the aperture of the housing.
Another object of the present invention is to provide a built-in lens set with improved controllability for operation that has an elastic connecting unit linking to the housing for providing a continuous elastic force to prevent the controllability of the driving mechanism of focus adjustment in the lens set from being affected by the backlash.
The shield assembly for a built-in lens set according to the present invention is located between a housing and a lens set mounted in the housing. The lens set includes an optical head with an outer rim. The housing has an aperture located on a location corresponding to the lens set. A protrusive enclosure is formed on an inner rim of the housing and surrounding the aperture and extending to the lens set for a preset distance. The shield assembly of the present invention includes a shield ring coupling with an exterior periphery of the optical head of the lens set and the protrusive enclosure, and an elastic connecting unit located between the shield ring and the housing.
The shield ring formed as an annular ring surrounding the exterior periphery of the optical head of the lens set and has a connecting end, a movable end corresponding to the connecting end, an outer rim connecting the movable end and the connecting end, and an inner rim corresponding to the outer rim and connecting the movable end and the connecting end. The connecting end is fixedly coupled on the optical head of the lens set, while the movable end is movably coupled with the exterior of the enclosure of the aperture.
The elastic connecting unit provides extensible connecting function between the shield ring and the housing, and includes a first end and a second end. The first end is fixedly mounted to the outer rim of the shield ring and the second end is fixedly mounted to the inner rim of the housing.
In one embodiment of the present invention, the elastic connecting unit consists of a plurality of spring elements. The spring elements are preferably located in an angular and equally spaced manner between the shield ring and the housing.
In one embodiment of the present invention, the elastic connecting unit may include at least one snap hook extending from the first end to the second end, and at least one latch trough extending from the second end to the first end. The snap hook and the latch trough form a movement limitation between the first end and the second end to ensure the lens set and the enclosure forming secured connection and positioning. In a preferred embodiment, the elastic connecting unit includes a plurality of spring elements. Each spring element is coupled with one latch trough and one snap hook.
In another embodiment of the present invention, the pair of the latch trough and the snap hook are formed in an exchanged manner; i.e. the elastic connecting unit includes at least one snap hook extending from the second end to the first end, and at least one latch trough extending from the first end to the second end.
In another embodiment of the present invention, the elastic connecting unit may include a plurality of rubber elements that are preferably located in an angular and equally spaced manner between the shield ring and the housing.
The foregoing, as well as additional objects, features and advantages of the present invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.